An on-line arrangement of transient isotachophoresis coupled to capillary zone electrophoresis was studied to improve concentration sensitivity when analysing the neuropeptides substance P and calcitonin gene related peptide in small volume samples. As there were big losses of the peptides due to adsorption at low concentrations, a new coating with plexiglas was investigated. It was also investigated if it was possible to directly inject the solid phase extraction-extract into the tITP-CZE system, without evaporating and reconstituting the extract. Finally, cerebrospinal fluid from rats was subjected to SPE and analysed in this analytical system. The plexiglas coating did not improve the loss of peptides due to adsorption to the capillary wall since the coating was not stable more than about 20 runs. Since the plexiglas coated capillaries were not stable, polyvinyl alcohol coated capillaries were used to prevent adsorption of the peptides. The peaks observed from the coupling of SPE to the tITP-CZE system, had approximately the same plate numbers as when no organic solvents were included in the running buffer system, indicating that this coupling is possible. A slight shift in migration times was observed, however, only with a coefficient of variance of approximately 1%. The recovery for SP and CGRP in the spiked samples was 98 and 51% respectively. Compared with a capillary zone electrophoresis system without any pre-concentration step, ITP-CZE enables a 30-fold increase of the injected sample volume, owning the possibility to inject larger sample volumes of lower concentration. The concentration sensitivity increased tenfold compared with a single CZE system and the LOD was estimated to 0.23 µmol/l for SP and 55 nmol/l for CGRP. With this analytical system the peptides in the cerebrospinal fluid were not detected, but when the sample was spiked with SP and CGRP, distinctive peaks were observed. To improve detection sensitivity and enable identification of unknown peaks, mass spectrometry is an interesting alternative to the UV absorbance detection used in this study.